1. Field of the Invention
The invention relates to an optical module; more particularly, the invention relates to a light source module.
2. Description of Related Art
In recent years, due to the advancement of the light-emitting efficiency and the increase in the service life, light-emitting diodes (LED) characterized by low power consumption, low pollution, high efficiency, fast response speed, compactness, light weight, and capability of being arranged on different types of surfaces have been extensively employed in the optical industry. The LED can normally serve as the light source in a variety of illumination apparatuses and flat panel displays utilized in daily lives, such as liquid crystal displays (LCD).
For instance, the backlight module of the LCD is a planar light source capable of providing evenly distributed illumination, where the basic principle is converting effective light from a linear light source or a point light source to the planar light source with high luminosity and high uniformity. Based on where the light source is located, the light source module may be categorized into a side-incident type and a direct type. Since the direct type backlight module has the simple structure and can have plural sets of light sources, the direct type backlight module is able to provide higher brightness and luminance and thus is often used in electronic products with large LCDs.
The existing direct type backlight module often makes use of secondary optical lenses to reduce the number of LEDs or lower the height of the optical cavity; however, the relevant costs may be correspondingly raised. Another conventional direct type backlight module does not require any secondary optical lens but requires the relatively thick optical cavity or more LEDs, thus lessening the reliability of the entire system.
China Patent No. 101418929B discloses a wide backlight source module featuring uniform distribution. China Patent No. 100389349C discloses a backlight module that includes a casing, a light source, and a reflector. China Patent No. 2729530Y discloses an opaque light shielding plate that has a reflection surface. Taiwan Patent No. I366039B1 discloses a direct type backlight module that includes a base, a plurality of light sources, and a transparent plate. Taiwan Patent No. 1256505 discloses a direct type backlight module that is constituted by a base, a plurality of point light sources, and a light mixing plate.